Cutting blades made of or coated with an amorphous metal

ABSTRACT

Metal alloys in an amorphous state are employed in the fabrication of cutting implements such as razor blades or knives. The implement may be formed from the amorphous metal or a coating of the amorphous metal may be applied. Such products may be formed from a ribbon of the amorphous metal alloy which has been prepared by quenching the molten metal or by coating the amorphous metal alloy on a suitable substrate such as by a sputtering procedure or vapor, chemical or electro-deposition of the alloy on the substrate.

DESCRIPTION OF PRIOR ART

The production of cutting implements by sharpening a piece of metal isan ancient art. Typically, the implement is fabricated from acrystalline metal which is formed to the desired shape and an edge isthen ground to a reduced thickness.

It is recognized that the properties and hence usefulness of the bladeare determined by the form of the edge and by the properties of thesubstance from which the blade is produced; these properties generallydepend upon the processing of the metal as well as upon its chemicalcomposition.

Scientific investigations have demonstrated that it is possible toobtain solid amorphous metals for certain alloy compositions, and asused herein, the term "amorphous" contemplates "solid amorphous." Anamorphous substance generally characterizes a non-crystalline or glassysubstance. In distinguishing an amorphous substance from a crystallinesubstance, diffraction measurements are generally suitably employed.

An amorphous metal produces a diffraction profile which varies slowlywith the diffraction angle and is qualitatively similar to thediffraction profile of a liquid or ordinary window glass. For example,FIG. 1 is the first peak of the diffracted intensity I as a function ofthe diffraction angle 2θ for amorphous Fe₄₀ Ni₄₀ P₁₄ B₆ as obtained froman x-ray diffractometer with MoKα radiation. Such a pattern is typicalfor amorphous metals. On the other hand, FIG. 2 represents thediffracted intensity I as a function of the diffraction angle 2θ forpolycrystalline Fe₄₀ Ni₄₀ P₁₄ B₆ over the same range of 2Θ. This morerapidly varying intensity is typical of crystalline materials.

These amorphous metals are in a metastable state. Upon heating to asufficiently high temperature, they crystallize with the evolution of aheat of crystallization and the diffraction profile changes from onehaving the glassy or amorphous characteristics to one having crystallinecharacteristics.

Additionally, suitably employed transmission electron micrography andelectron diffraction can be used to distinguish between the amorphousand the crystalline state.

It is possible to produce a metal which is a two-phase mixture of theamorphous and the crystalline state; the relative proportions can varyfrom totally crystalline to totally amorphous. An amorphous metal, asemployed herein, refers to a metal which is primarily amorphous but mayhave a small fraction of the material present as included crystallites.

For a suitable composition, proper processing will produce a metal inthe amorphous state. One typical procedure is to cause the molten alloyto be spread thinly in contact with a solid metal substrate such ascopper or aluminum so that the molten metal looses its heat to thesubstrate.

When the alloy is spread to a thickness of ˜0.002 inch, cooling rates ofthe order of 10⁶ ° C/sec are achieved. See, for example, R. C. Ruhl,Mat. Sci. & Eng. 1, 313 (1967), which discusses the dependence ofcooling rates upon the conditions of processing the molten metal. For analloy of proper composition and for a sufficiently high cooling rate,such a process produces an amorphous metal. Any process which provides asuitably high cooling rate can be used. Illustrative examples ofprocedures which can be used to make the amorphous metals are therotating double rolls described by H. S. Chen and C. E. Miller, Rev.Sci. Instrum. 41; 1237 (1970) and the rotating cylinder techniquedescribed by R. Pond, Jr. and R. Maddin, Trans. Met. Soc., AIME 245,2475 (1969).

Alternatively, a deposition technique can be used to produce anamorphous metal. Two such techniques are vapor deposition andsputtering. In vapor deposition, the metal to be deposited is placed ina high vacuum and is heated to a temperature such that its vaporpressure is at least 10⁻² mm Hg; this vapor is then condensed to thesolid state on sufficiently cold surfaces exposed to the vapor. Insputtering, the metal to be deposited and the substrate upon which it isto be deposited are placed in a partial vacuum, usually of the order of1 mm Hg. A high potential is applied between an electrode and the metalto be deposited, and the gaseous ions created by the high potentialstrike the surface of the metal with an energy sufficient to cause atomsfrom the metal to enter the vapor phase; these atoms then condense tothe solid state on surfaces exposed to the vapor. Both the vapordeposition and the sputtering techniques are described in detail inHandbook of Thin Film Technology, L. I. Maissel and R. Glang, McGrawHill, 1970. Similarly, chemical (electro-less) or electro-deposition ofa suitable alloy composition from a solution can also lead to anamorphous alloy.

SUMMARY OF THE INVENTION

The invention has as its primary object the provision of cuttingimplements which are composed of, or are coated with an amorphous metal.

Additional objects and advantages will be apparent from thespecification and claims.

One class of cutting implements which is of particular interest is thattypified by safety razor blades. A strip or sheet of an amorphous metalwith a thickness of about 0.001 to 0.005 inch can be sharpened so as toproduce a razor blade. Further treatment such as the sputtering on of acrystalline or amorphous metal coating or the application of afluorocarbon coating may be used to produce the finished blade.

We have discovered that amorphous metals are exceptionally well-suitedto use for razor blades since compositions with high as-formed hardness,ductility, a high elastic limit and good corrosion resistance can beselected. Additionally, these amorphous metals are more homogeneous thancommon crystalline materials for the dimensions characteristic of thesharpened edge of a razor blade. Greater hardness and better corrosionresistance than the stainless steel blades now in use can be achieved.

Strips from which the blades are made can be obtained by any of varioustechniques. Most suitable is the quenching from the melt of a continuousstrip by, for example, using a pair of rotating rolls or by squirtingthe molten metal onto the outside of a rapidly rotating cylinder.

Additionally, razor blades can be produced which consist of sharpenedcrystalline metal or amorphous metal blades with an amorphous metal filmdeposited on top of the edge, for example, by sputtering.

Further, a blade can be produced by sharpening after the amorphous metalcoating has been applied to a crystalline substrate, by sputtering orvapor deposition, for example.

Cutting blades such as common knives can be produced with an amorphousmetal coating applied, for example, by sputtering or electro-depositionso as to improve the properties of the surface.

Cutting blades other than razor blades can also be produced bysharpening an amorphous metal strip or sheet. Further, a sandwichconstruction where the amorphous metal is held between two layers of asofter material could be used to make blades.

It has been found that metal alloys which are partially amorphous cansometimes also have the desirable properties of high hardness, highstrength, high elastic limit, and ductility which can be obtained withthe fully amorphous state. These alloys may be a mixture of theamorphous and crystalline states because of several possible reasons.The composition may be one which for obtainable quench rates ordeposition parameters does not give a totally amorphous substance, or arelatively low quench rate may have been employed, or part of the samplemay have been recrystallized upon a heat treatment of the sample. Atypical x-ray diffraction pattern for such an amorphous-crystallinemixture is shown in FIG. 3. It is a superposition or summation of anamorphous pattern and a crystalline pattern. Resolving the two patternsand measuring the relative integrated intensities indicates theapproximate relative percentages of the two structures. Additionally,transmission electron micrography and diffraction can also be used toestimate the percent of each phase. Further, the measured heat ofcrystallization will be proportional to the fraction that is amorphous.

The articles described above can be made from such anamorphous-crystalline mixture where the crystalline fraction is lessthan 50%.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 illustrates the diffraction intensity of an amorphous Fe₁₀ Ni₄₀P₁₄ B₆ metal.

FIG. 2 illustrates the diffracted intensity of the crystalline metal ofFe₄₀ Ni₄₀ P₁₄ B₆.

FIG. 3 is an x-ray diffraction pattern for a partially crystalline metalalloy of Ni₇₇ P₁₄ B₆ Al₃.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In accordance with the invention, an amorphous metal strip can besharpened to form razor blades of excellent edge characteristics: highresistance to mechanical damage and superior corrosion resistance. Inproduction, for example, an amorphous metal strip which is 0.002 inchthick and about 1/4 inch wide can be sharpened on one edge and then cutinto lengths of about 1.75 inches. Alternatively, strips of greaterwidth can be sharpened on both edges.

Strips of many different alloy compositions can be used for razorblades. The preferred alloys will consist of primarily iron, nickel,cobalt, chromium, vanadium and mixtures thereof. Alloys of particularinterest contemplated by the invention are those having the generalformula M_(a) X_(b) wherein M may be any combination of Ni, Fe, Co, Crand/or V, X will be elements such as P, B, C, Si, Al, Sb, Sn. In, Geand/or Be and a and b represent atomic percent in which a will generallyrange from 90 to 65 atomic percent and b will range from 10 to 35 atomicpercent. Preferably, a will vary from about 84 to about 73 atomicpercent while b will vary from about 16 to about 27 atomic percent.

Examples of some of the preferred compositions include Ni₇₅ P₁₆ B₆ Al₃ ;Ni₅₀ Fe₂₈ P₁₄ B₆ Al₂ ; Cr₂₄ Fe₂₄ Ni₃₀ P₁₄ B₄ C₂ Si₂ ; Fe₃₈ Cr₃₈ P₁₅ C₄B₂ Al₃ ; Fe₄₀ Ni₄₀ P₁₄ B₆ ; and Fe₃₀ Co₂₀ Cr₂₈ P₁₄ B₆ Al₂.

The alloying elements normally used in steels, such as Mo, Mn, Ti, W andCu, can also be included in these compositions as a partial replacementfor any of the metals Ni-Fe-Cr-Co-V. In replacing the latter with theformer, preferably not more than about one-third of the latter metals inatomic percent is replaced with the former.

An alternate embodiment of the invention resides in coating a metalsubstrate with an amorphous metal layer such as by the sputtering of athin film (about 50 to 300A. thick) of metal which is at least 50%amorphous onto the edge of an already sharpened amorphous or crystallinerazor blade. The general compositions of such coating alloys areessentially those listed above in connection with the amorphous strips.Preferred coating compositions are, for example, Cr₈₀ P₁₅ B₅ ; Fe₂₀ Cr₆₀P₂₀ ; Cr₆₅ Ni₁₀ P₁₅ Si₁₀ and Cr₇₇ P₁₃ B₅ Si₅.

Still another embodiment resides in the deposition of an amorphouscoating of the general compositions listed above on various articles ofcutlery. For example, a composition such as Ni₈₀ P₂₀ can beelectro-deposited onto a formed utensil such as a knife or instead acomposition such as Cr₆₀ Ni₂₀ P₁₅ B₅ can be sputtered thereon.

The invention will be further described by reference to the followingspecific examples. It should be understood, however, that although theseexamples may describe in detail certain preferred operating conditionsand/or materials and/or proportions, they are provided primarily forpurposes of illustration and the invention, in its broader aspects, isnot limited thereto. Parts expressed are parts by atomic percent unlessotherwise stated.

EXAMPLE 1

A molten alloy of composition Ni₁₈ Fe₃₀ P₁₄ B₆ Al₂ at a temperature of1,050° C. is quenched to the amorphous state by using the rotatingdouble roll apparatus described by Chen and Miller in Rev. Sci. Instrum.41 1237 (1970). An argon pressure of 8 psi is used to squirt the moltenmetal through a 0.010 inch hole in the bottom of a fused silica tubeinto the nip of the 2 inch diameter, 3 inch long double rolls which areat room temperature and rotating at about 1,400 rpm. A force of about100 lbs. is applied so as to push the rolls towards each other. Themolten metal is thus quenched to a 0.002 inch thick ribbon of amorphousmetal of the same composition. The edge of the ribbon is sheared off soas to provide a straight edge and a cutting edge is ground and honed onthe sheared edge of the strip in a manner conventionally used to sharpenrazor blades. In sharpening, care is taken such that any part of themetal strip does not reach a temperature above 340° C. The strips arecut to the desired length for individual blades. The blade may besuitably employed at this juncture. However, the blade may be furtherprocessed after sharpening such as by the deposition of an amorphous orcrystalline metal film of about 150° A. on the cutting edge. Thiscoating may be applied by sputtering or vapor deposition, as descrbed inthe aforementioned Maissel and Glang text. A fluorocarbon coating mayalso be applied such as disclosed in U.S. Pat. No. 3,071,856 -- careagain being taken to avoid excess temperature which would causecrystallization of the amorphous metal.

EXAMPLE 2

A 0.004 inch thick strip of stainless steel is ground and honed toproduce a razor blade with a conventionally shaped edge. An alloy ofcomposition Cr₇₈ P₁₄ B₅ Si₃ is sputtered onto the edge of the bladewhich is kept at a temperature below 100° C. in the manner described inChapter 4 of the Maissel and Glang text, so as to produce a metal filmof this alloy composition which is more than 50% amorphous and has anaverage thickness of 200 A. on the edge of the blade. A fluorocarboncoating in the manner disclosed in Example 3 of U.S. Pat. No. 3,071,856is applied to the blade.

A similar procedure was followed for a 0.002 inch thick blade ofamorphous Ni₅₀ Fe₂₈ P₁₄ B₆ Al₂.

Similarly, Cr₅₈ Ni₁₈ P₁₄ B₆ Si₄ is sputtered onto other ground stainlesssteel and amorphous Ni₅₀ Fe₂₈ P₁₄ B₆ Al₂ blades which are then coatedwith a fluorocarbon.

EXAMPLES 3-8

Following the procedure of Example 1, amorphous strips suitable forforming of razor blades are prepared from the alloys shown in Table 1.Some examples, as indicated, are coated.

                  TABLE I                                                         ______________________________________                                                              Coating                                                 Ex.  Alloys (atomic %)                                                                              (if any)                                                ______________________________________                                        3    Fe.sub.39 Ni.sub.39 P.sub.16 B.sub.4 Si.sub.2                            4    Fe.sub.39 Ni.sub.39 P.sub.16 B.sub.4 Si.sub.2                                                  Cr.sub.80 P.sub.15 B.sub.5 (sputtered)                  5    Fe.sub.30 Ni.sub.20 Cr.sub.28 P.sub.14 B.sub.6 Al.sub.2                                        Cr.sub.65 Ni.sub.10 P.sub.15 Si.sub.10 (sputtered)                            and thereafter coated                                                         with polytetrafluoro-                                                         alkylene)                                               6    Fe.sub.38 Cr.sub.38 P.sub.15 C.sub.4 B.sub.2 Al.sub.3                                          Cr.sub.80 P.sub.15 B.sub.5 (sputtered)                                        and thereafter coated                                                         with polytetrafluoro-                                                         ethylene                                                7    Ni.sub.75 P.sub.16 B.sub.6 Si.sub.1 Al.sub.2                                                   Cr.sub.80 P.sub.15 B.sub.5 (sputtered)                                        and thereafter coated                                                         with polytetrafluoro-                                                         ethylene                                                8    Cr.sub.40 Co.sub.36 P.sub.14 B.sub.6 Al.sub.4                                                  Cr (sputtered)                                          ______________________________________                                    

EXAMPLE 9

A stainless steel knife with a high polish is cleaned by washing withtrichloroethylene and dried. An amorphous film of Cr₈₀ P₁₅ B₅ issputtered on the entire blade. The film thickness is 1,000 A. Arelatively tough and durable mar-resistant coating is produced.

We claim:
 1. A cutting implement comprising a metal which is at least50% amorphous, characterized in that the metal has the composition M_(a)X_(b), where M is at least one element selected from the groupconsisting of Ni, Fe, Co, Cr and V, X is at least one element selectedfrom the group consisting of P, B, C, Si, Al, Sb, Sn, In, Ge and Be, aranges from 65 atomic percent to 90 atomic percent and b ranges from 10atomic percent to 35 atomic percent.
 2. The cutting implement of claim 1in which a ranges from about 73 atomic percent to 84 atomic percent andb ranges from about 16 atomic percent to 27 atomic percent.
 3. Thecutting implement of claim 1 in the form of a razor blade.
 4. A cuttingimplement having deposited thereon a metal film which is at least 50%amorphous, characterized in that the metal has the composition M_(a)X_(b), where M is at least one element selected from the groupconsisting of Ni, Fe, Co, Cr and V, X is at least one element selectedfrom the group consisting of P, B, C, Si, Al, Sb, Sn, In, Ge and Be, aranges from 65 atomic percent to 90 atomic percent and b ranges from 10atomic percent to 35 atomic percent.
 5. The cutting implement of claim 4in which a ranges from about 73 atomic percent to 84 atomic percent andb ranges from about 16 atomic percent to 27 atomic percent.
 6. Thecutting implement of claim 4 in the form of a razor blade.
 7. Thecutting implement of claim 4 in which the metal film ranges from about50A to 300A in thickness. .Iadd.
 8. A cutting implement comprising ametal which is at least 50% amorphous, characterized in that the metalhas the composition M_(a) X_(b), where M is at least one elementselected from the group consisting of Ni, Fe, Co, Cr and V, up to about1/3 of which may be replaced by alloying elements normally used insteels, X is at least one element selected from the group consisting ofP, B, C, Si, Al, Sb, Sn, In, Ge and Be, "a" ranges from 65 atomicpercent to 90 atomic percent and "b" ranges from 10 atomic percent to 35atomic percent. .Iaddend..Iadd.
 9. A cutting implement having depositedthereon a metal film which is at least 50% amorphous, characterized inthat the metal has the composition M_(a) X_(b), where M is at least oneelement selected from the group consisting of Ni, Fe, Co, Cr, and V, upto about 1/3 of which may be replaced by alloying elements normally usedin steels, X is at least one element selected from the group consistingof P, B, C, Si, Al, Sb, Sn, In, Ge and Be, "a" ranges from 65 atomicpercent to 90 atomic percent and "b" ranges from 10 atomic percent to 35atomic percent. .Iaddend. .Iadd.
 10. The cutting implement of claim 8 inwhich up to about 1/3 of M is replaced by at least one element selectedfrom the group consisting of molybdenum, manganese, titanium, tungstenand copper. .Iaddend..Iadd.
 11. The cutting implement of claim 9 inwhich up to about 1/3 of M is replaced by at least one element selectedfrom the group consisting of molybdenum, manganese, titanium, tungstenand copper..Iaddend.